This invention is directed to the preparation of an isocyanate complex which is further reacted by coupling with an aminoheterocycle and the product processed to convert one crystal form of the resultant sulfonylurea product to a more stable crystal product form.
There is a continuing need to discover new processes for the preparation of the highly active sulfonylurea class of compounds where the preparation offers distinct advantages that add to their desirability. Already known in the art are U.S. Pat. Nos. 4,546,179 and 5,157,119 that pertain to a process to prepare sulfonylureas. The purity and crystal form obtained by these processes may not be acceptable for formulation development.